8/9/2019 Proximus Tm Eng http://slidepdf.com/reader/full/proximus-tm-eng 1/68 808 B – 08/01 A – pag. 1/68 0 Water cooled screw chillers PROXIMUS “EVOLUTION” SE (Standard Efficiency) 111.1÷596.2 Cooling capacity from 388 a 2093 kW XE (High Efficiency) 111.1÷596.2 Cooling capacity from 431 to 2196 kW 50Hz – Refrigerant: R –410A Product Manual Date: January 2008 Su ersedes: 807 B – 04/11 C 808 B – 08/01 A McQuay is participating in the Eurovent Certification Programme. Product are as listed in the Eurovent Directory of Certified Products and on the web site www.eurovent-certification.com
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
McQuay is participating in the Eurovent Certification Programme.Product are as listed in the Eurovent Directory of Certified Productsand on the web site www.eurovent-certification.com
New water cooled screw chillers McQuay PROXIMUS“EVOLUTION”
McQuay International introduces its new water cooled screw chillers equipped with new compressors.
McQuay water cooled PROXIMUS “EVOLUTION” is a new range of chillers using the last generation of
McQuay StarGateTM
single screw compressors. They are manufactured by McQuay to satisfy the requirements
of the consultants and the end users. McQuay PROXIMUS “EVOLUTION” units are designed to minimise
energy costs while maximising the refrigeration capacities. Once again McQuay has developed a line of chillers
unsurpassed in performance and quality that will meet the most stringent requirements of comfort cooling and
process applications.
McQuay’s chiller design experience, combined with outstanding features, makes the PROXIMUS “EVOLUTION”
chiller unmatched in the industry.
R–410A refrigerant – Ecological and efficientMcQuay has optimized Stargate
TM compressors to operate with R–410A, ecological refrigerant with zero ODP
(Ozone Depletion Potential) and very low GWP (Global Warming Potential), that means low value of the “direct
effect” in the formula of TEWI (Total Equivalent Warming Impact).
This refrigerant is safe and chemically stable and is listed in ASHRAE Standard-34 (Number Designation and
Safety Classification For Refrigerants) as “A-1” refrigerant: lowest toxicity, non-flammable.
An essential feature of this refrigerant is its very high cooling capacity: for example R–410A has nearly 50%
higher cooling capacity in comparison to R22.
The research also indicates a favourable energy consumption when used with low
condensing temperatures and this gives money saving and good premises for a very low
value of the “indirect effect” in the TEWI formula.
An advantage is the high heat transfer coefficients (found also during the test) in the
evaporator and condenser, therefore providing further potential for increased efficiencies.
This refrigerant is a blend of two different types of refrigerant: 50% of R32 and 50% of
R125.
Because of the negligible temperature glide (< 0,15 °C), the general usability can be seensimilar to a pure refrigerant (as HFC134a) so this refrigererant doesn’t present any
maintenance problem even if it’s a refrigerants blend .
Significant differences in the thermodynamic properties for this refrigerant (e.g. mass and
volume flow, vapour density, pressure levels) have been evaluated and design changes to
the single-screw compressor, piping and controls have been made to optimize the chiller’s performance and
reliability.
Lower noise – higher flexibilityThe compressor allows a constant gas flow. This compression process eliminates completely gas pulsations,
that are one of the main reasons for quiet operation. The oil injection also results in a significant mechanical
noise reduction, in a perfect moving parts cooling and clearances sealing to reach very high volumetric
efficiency.The gas compressor discharge chambers are designed to act as attenuators, based on the harmonic wave
principle with destructive interference, thus always resulting almost equal to zero. The extremely low noise
compressor performance allows the use of Proximus “Evolution” chiller for all applications.
Lower vibration levels – higher reliabilitySince the moving components in the McQuay Single Screw Compressor are purely rotational and the loads are
basically balanced, the dynamic forces and vibrations created by the system are very low. This reduced
vibration results in less movement to refrigerant lines and other parts of the system.
The extremely low vibration levels, inherent with the single-screw design, will not pass through system piping
and allow objectionable resonated sound to be carried into the building.
• Zero clearance fit between the gaterotor/s and main screw rotor virtually eliminates leakage between
the high and low-pressure sides during compression. Special gaterotor material made from an
advanced composite, temperature stable material makes a zero clearance design possible.
• The Proximus “Evolution” water-cooled chiller is equipped with the most advanced means of refrigerant
flow control available. An electronic expansion valve coupled with the MicroTech II C Plus controller's
control logic provides excellent operating efficiencies both at full and part load operation.
• Infinite unloading matches compressor capacity to load.
• Full factory testing of the unit with water hookups helps provides a trouble-free start-up. Extensive
quality control checks during testing means that each equipment protection and operating control is
properly adjusted and operates correctly before it leaves the factory. Factory-installed options minimize
field expenses and startup labor.
• The rugged design of the single-screw compressor allows it to be tolerant of liquid slugging. Screw
chiller will start and operate under conditions that would often destroy other compressors.• Very low loading enhances the bearing and compressor reliability. Balanced forces result in the
elimination of the high loads inherent in twin-screw compressors.
• Integral to the basic design of the single-screw compressor, the main screw rotor shaft and the
gaterotor shaft/s cross at right angles in the compressor. The result is ample space to locate heavy duty
bearings and increase compressor reliability since no limitations are placed on bearing design as found
Code requirements – Safety and observant of laws/directives
All water cooled units are designed and manufactured in accordance with applicable selections of the following
which are equivalent to American Air-conditioning industry applicable codes:
Rating of chillers: EN 12055.
Construction of pressure vessel: Pressure Equipment 97/23/EC (PED).
Machinery Directive: 98/37/EC
Low Voltage: 2006/95/EC
Electromagnetic Compatibility: 2004/108/EC
Electrical & Safety codes: IEC 60204–1.
Manufacturing Quality Stds: ISO 9001:2000.
Certifications All units manufactured by McQuay Italia S.p.A. are CE marked, complying with European directives in force,
concerning manufacturing and safety. On request units can be produced complying with laws in force in non
European countries (ASME, GOST, etc.), and with other applications, such as naval (RINA, etc.).
GENERAL CHARACTERISTICS
StructureThe chiller is equipped with brackets directly installed on heat exchangers. The evaporator and the suction
piping are appropriately insulated to prevent condensation. Unit is provided with lifting holes.
Screw compressorsThe Stargate
TM single-screw compressor has a well balanced compression mechanism which gives main
bearing design life of 3-4 times greater than twin-screws and eliminates expensive and complicated thrust
balancing schemes.
Oil injection is used for these compressors in order to get high EER at high condensing pressure. The oilsupplied to the compressor performs three basic functions: oil for capacity control actuation, oil for bearing
lubrication, oil for sealing. The oil is injected via fixed ports in the casing around the rotor.
Compressors have an infinitely variable capacity control down to 25% of its total capacity. This control is made
by means of capacity slides controlled by microprocessors.
The unit is furnished with an external (for Frame 4) or integrated (for Frame 3200) high efficiency oil separator to
maximise oil extraction.
The compressor is provided with a liquid injection circuit to reach oil cooling.
Standard start is star-delta type.
EvaporatorThe units are supplied with optimised shell and tubes evaporator pass that allows a perfect oil circulation and so
a perfect oil return to the compressor. It is direct expansion with refrigerant inside the tubes and water outside(shell side) with carbon steel tube sheets, with straight copper tubes that are spirally wound internally for higher
efficiencies, expanded on the tube plates. The external shell is covered with a closed cell insulation material.
Screw
Gaterotor Gaterotor
A
B
BB
B
AA
B
BB
B
A
High Axial and Radial thrusts inTwinScrew Compressor
Single Screw Compressor Single Screw Compressor Twin Screw Compressor
Each evaporator has 1 or 2 circuits, one for each compressor and is manufactured in accordance to PED
approval. The evaporator water outlet connections are provided with Victaulic Kit.
CondensersCondensers are shell and tubes cleanable, through-tube type. The unit has indenpendent condensers, one per
circuit. Each condenser has a carbon steel and seamless, integrally finned high efficiency copper tubes, roll
expanded into heavy carbon steel tube sheets. Water heads are removable and include vent and drain plugs.Condensers come complete with liquid shut-off valve, spring loaded relief valve.
Electronic expansion valve (EEXV)Proximus “Evolution” water cooled chiller is equipped with the most advanced electronic expansion valve to
achieve precise control of refrigerant mass flow. As today’s system requires improved energy efficiency, tighter
temperature control, wider range of operating conditions and incorporate features like remote monitoring and
diagnostics, the application of electronic expansion valves becomes mandatory. Proximus “Evolution” electronic
expansion valve proposes features that makes it unique: short opening and closing time, high resolution,
positive shut-off function to eliminate use of additional solenoid valve, highly linear flow capacity, continous
modulation of mass flow without stress in the refrigerant circuit and corrosion resistance stainless steel body.
EEXV strength point is the capacity to work with lower ΔP beetwen high and low pressure side, than a
thermostatic expansion valve. The electronic expansion valve allows to system to work with low condenserpressure (winter time) without any refrigerant flow problems and with a perfect chilled water leaving temperature
control. This feature becomes more important in Proximus “Evolution” that works with R–410A: the research
indicates a favourable energy consumption when this refrigerant is used with low condensing temperatures.
Refrigerant CircuitEach unit has 1 or 2 independent refrigerant circuits with one compressor per circuit, including:
• High and low pressure switches
• Moisture liquid indicator
• High efficiency oil separator
• Replaceable core filter-drier
• Electronic expansion valve
Electrical control panel
Power and control are located into two sections of the main panel that is manufactured to insure protection for
all weather conditions.
The power panel is fitted with an interlocked door main isolator to prevent access while power supply is on.
Electrical panel is IP54.
Power section includes
The power section includes contactors, all compressors fuses and control circuit transformer. Additional space
is provided for an easy installation of the various optional accessories provided to enhance the Proximus
“Evolution” units capabilities.
MicroTech II C Plus controllerMicroTech II C Plus controller is installed as standard on all the units; it can be used to modify unit set points
and check control parameters. A display illustrates the machine's operating status, programmable values and
setpoints e.g. temperatures, and pressures of fluids (water, refrigerant). Device controls maximise the McQuay
chillers energy efficiency and reliability characteristics. It uses sophisticated software with predictive logic to
select the most energy efficient combination of compressor, expansion device and condenser fan to keep stable
operating conditions and maximise energy efficiency. The compressors are automatically rotated to ensure
equal operating hours. MicroTech II C Plus protects critical components in response to external signals from its
system sensors measuring: motor temperatures, refrigerant gas and oil pressures, correct phases sequence
• Service report displaying all running hours and general conditions
• Memorized alarm history to facilitate the fault’s analysis
• Remote full featured versions of the LCD terminal are available for a comfortable check and control of
the unit over RS488 line.
Standard Configuration (furnished on basic unit)
Star Delta Compressors starter – For low inrush current and reduced starting torque.
Phase monitor – The phase monitor controls phase sequence and phase loss.
Evaporator connection water side Victaulic – Hydraulic joint with gasket for an easy and quick water
connection.
Double Set Point version (CB) – Dual leaving glycol mixture temperature setpoints. The lower setpoint can go
down to 0°C. This option needs 20mm thicked evaporator insulation (option on request).1 pass condensers for SE ST units 211.1-251.1-293.1 and 424.2÷596.2.
2 passes condensers for SE ST units 111.1÷186.1 and 231.2÷385.2, and for XE ST units.
Hour run meter – Digital compressors hour run meter.
General fault relay – Contactor for the alarm warning.
Alarm from external device – Microprocessor is able to receive an alarm signal from an external device
(pump, etc...). User can decide if this alarm signal will stop or not the unit.
Discharge line check valves
Options (on request)
Partial heat recovery – Enabled through a shell & tubes type sited between the compressor and the
condenser, completely dedicated to the heat recovery. These allow hot water to be produced up to a maximum
temperature of 58°C, and to have a very economic solution.
Evaporator electric heater – Electric heater controlled by a thermostat to protect the evaporator from freezing
down to -28°C ambient temperature.
Compressor thermal overload relays - Safety devices against compressor motor overloading in addition to
the normal protection envisaged by the electrical windings.
Amp and Volt Meter - Digital meters of unit drawn amperes and voltage values, installed on the electrical
control panel.
Power factor correction - Installed on the electrical control panel to ensure it complies with the plant rules.(McQuay advices maximum 0,9).
Flow switch - Supplied separately to be wired and installed on the evaporator water piping (by the customer).
Suction line shut-off valves – Suction shut-off valve installed on the suction part of the compressor to facilitate
maintenance operations.
Discharge line shut-off valves – Discharge shut-off valve installed on the discharge part of the compressor to
facilitate maintenance operations.
Cu-Ni 90-10 condenser – To work with sea water the heat exchangers are fitted with Cu-Ni tubes and special
protection inside the end covers.
Rubber type antivibration mounts - Supplied separately, these are positioned under the base of the unit for
“floor” installation.
Sound proof cabinet - Made of sheet metal and internally insulated, the cabinet is "integral kind" ( around the
whole chiller, not only around the compressors ) to reach the best performance in noise reduction.
Current Limit / Display – This option allows to monitor the chiller absorbed current with possibility to set a limit
value. This option excludes the Demand Limit.
20mm thicked evaporator insulation – Useful in really heavy operating conditions.
2 passes condensers working with 9÷12 °C water ΔT for SE ST units 211.1-251.1-293.1 and 424.2÷596.2
4 passes condensers working with 9÷12 °C water ΔT for SE ST units 111.1÷186.1 and 231.2÷385.2, and
for XE ST units
Witness tests - The units are normally tested at the test bench prior to the shipment. On request, a second testcan be carried out, at customer’s presence, in accordance with the procedures indicated on the test form. (Not
available for units with Glycol mixtures).
Soft start – Electronic starting device to prevent mechanical stress of the motor. An overload protection is
included (no need of compressors thermal relays).
Over / Under Voltage – Phase monitor to control the minimum and maximum voltage value that the user can
set.
Supervising systems (on request)
PlantVisor TM
:Solution for tele-maintenance and supervisory
MicroTech II C Plus can be monitored locally or via modem or GSM by PlantVisor TM
supervision program.
PlantVisorTM is compatible with all Windows based systems.
It allows the followings functions:
• Unit status monitoring
• Circuits status monitoring
• Set-points modification
• Alarms display.
MicroTech II C Plus remote controlMicroTech II C Plus is able to communicate to BMS (Building Management System) based on the most
common protocols as:
• CARELNative
• ModbusRTU
• LonWorks, now also based on the international 8040 Standard Chiller Profile and LonMark Technology
• BacNet BTP certifief over IP and MS/TP (class 4)
• Ethernet TCP/IP and SNM.
Chiller Sequencing
MicroTech II control family allows an easy plug-in sequencing technology based on digital or serial field panelMCS (McQuay Chiller Sequences)
Digital Step Inverter to sequence and rotate up to 11 chillers, based on 1 or 2 configurable input sensors. A very
interesting low level full configurable digital field system. Monitorable by Plant Visor.
CSC II (Chiller System Controller II)
Serial sequences for up to 5 MTII chillers. Full featured field serial device to sequence, optimize and monitor a
little group of McQuay chillers (check your catalogue for compatibility and features). Monitorable by Plant Visor.
Allowed voltage tolerance ± 10%. Voltage unbalance between phases must be within ± 3%.
Nominal current in cooling mode is referred to installation with 25kA short circuit current and is basedon the following conditions: evaporator 12°C/7°C; ambient 35°C.
Maximum starting current: starting current of biggest compressor + 75% of maximum current of theother compressor.
Maximum current for wires sizing: (compressors full load ampere) x 1,1.
Notes
Recommended fuses (IEC 269-2: 1.6 times largest compressor fuse size)
ELECTRICALSPECIFICATIONS
PROXIMUS“EVOLUTION” SE ST
231.2 251.1 254.2 279.2 293.1
Phase 3~ 3~ 3~ 3~ 3~
Frequency Hz 50 50 50 50 50
Voltage V 400 400 400 400 400
Minimum % -10% -10% -10% -10% -10%
Power Supply
VoltageTolerance Maximum % +10% +10% +10% +10% +10%
Maximum starting current A 610 656 638 638 656
Nominal running current cooling A 289 330 325 352 386
Maximum running current A 358 381 393 428 445Unit
Maximum current for wires sizing A 416 419 432 470 489
Allowed voltage tolerance ± 10%. Voltage unbalance between phases must be within ± 3%.
Nominal current in cooling mode is referred to installation with 25kA short circuit current and is basedon the following conditions: evaporator 12°C/7°C; ambient 35°C.
Maximum starting current: starting current of biggest compressor + 75% of maximum current of theother compressor.
Maximum current for wires sizing: (compressors full load ampere) x 1,1.
Notes
Recommended fuses (IEC 269-2: 1.6 times largest compressor fuse size)
Allowed voltage tolerance ± 10%. Voltage unbalance between phases must be within ± 3%.
Nominal current in cooling mode is referred to installation with 25kA short circuit current and is based
on the following conditions: evaporator 12°C/7°C; ambient 35°C.Maximum starting current: starting current of biggest compressor + 75% of maximum current of theother compressor.
Maximum current for wires sizing: (compressors full load ampere) x 1,1.
Notes
Recommended fuses (IEC 269-2: 1.6 times largest compressor fuse size)
ELECTRICAL SPECIFICATIONSPROXIMUS
“EVOLUTION” SE ST462.2 508.2 549.2 596.2
Phase 3~ 3~ 3~ 3~
Frequency Hz 50 50 50 50
Voltage V 400 400 400 400Minimum % -10% -10% -10% -10%
Power Supply
Voltage ToleranceMaximum % +10% +10% +10% +10%
Maximum starting current A 984 984 1035 1035
Nominal running current cooling A 604 654 701 749
Maximum running current A 706 764 824 886Unit
Maximum current for wires sizing A 778 840 906 975
Phase 3~ 3~ 3~ 3~
Voltage V 400 400 400 400
Minimum % -10% -10% -10% -10%Voltage Tolerance
Maximum % +10% +10% +10% +10%
Maximum running current A1)325
2)388
1)388
2)388
1)388
2)458
1)458
2)458
Compressor
Starting method Open Star-Delta
Allowed voltage tolerance ± 10%. Voltage unbalance between phases must be within ± 3%.
Nominal current in cooling mode is referred to installation with 25kA short circuit current and is basedon the following conditions: evaporator 12°C/7°C; ambient 35°C.Maximum starting current: starting current of biggest compressor + 75% of maximum current of theother compressor.
Maximum current for wires sizing: (compressors full load ampere) x 1,1.
Notes
Recommended fuses (IEC 269-2: 1.6 times largest compressor fuse size)
Allowed voltage tolerance ± 10%. Voltage unbalance between phases must be within ± 3%.
Nominal current in cooling mode is referred to installation with 25kA short circuit current and is basedon the following conditions: evaporator 12°C/7°C; ambient 35°C.
Maximum starting current: starting current of biggest compressor + 75% of maximum current of theother compressor.
Maximum current for wires sizing: (compressors full load ampere) x 1,1.
Notes
Recommended fuses (IEC 269-2: 1.6 times largest compressor fuse size)
ELECTRICAL SPECIFICATIONSPROXIMUS
“EVOLUTION” XE ST251.1 279.2 293.1 307.2
Phase 3~ 3~ 3~ 3~
Frequency Hz 50 50 50 50Voltage V 400 400 400 400
Minimum % -10% -10% -10% -10%
Power Supply
Voltage ToleranceMaximum % +10% +10% +10% +10%
Maximum starting current A 656 636 656 674
Nominal running current cooling A 315 347 367 381
Maximum running current A 376 422 442 467Unit
Maximum current for wires sizing A 414 464 486 514
Phase 3~ 3~ 3~ 3~
Voltage V 400 400 400 400
Minimum % -10% -10% -10% -10%Voltage Tolerance
Maximum % +10% +10% +10% +10%
Maximum running current A 388
1)225
2)225 458
1)225
2)274
Compressor
Starting method Open Star-Delta
Allowed voltage tolerance ± 10%. Voltage unbalance between phases must be within ± 3%.
Nominal current in cooling mode is referred to installation with 25kA short circuit current and is basedon the following conditions: evaporator 12°C/7°C; ambient 35°C.
Maximum starting current: starting current of biggest compressor + 75% of maximum current of theother compressor.
Maximum current for wires sizing: (compressors full load ampere) x 1,1.
Notes
Recommended fuses (IEC 269-2: 1.6 times largest compressor fuse size)
Maximum current for wires sizing A 566 603 639 692
Phase 3~ 3~ 3~ 3~
Voltage V 400 400 400 400
Minimum % -10% -10% -10% -10%Voltage Tolerance
Maximum % +10% +10% +10% +10%
Maximum running current A1)274
2)274
1)274
2)310
1)310
2)310
1)325
2)325
Compressor
Starting method Open Star-Delta
Allowed voltage tolerance ± 10%. Voltage unbalance between phases must be within ± 3%.
Nominal current in cooling mode is referred to installation with 25kA short circuit current and is based
on the following conditions: evaporator 12°C/7°C; ambient 35°C.Maximum starting current: starting current of biggest compressor + 75% of maximum current of theother compressor.
Maximum current for wires sizing: (compressors full load ampere) x 1,1.
Notes
Recommended fuses (IEC 269-2: 1.6 times largest compressor fuse size)
ELECTRICAL SPECIFICATIONSPROXIMUS
“EVOLUTION” XE ST462.2 508.2 549.2 596.2
Phase 3~ 3~ 3~ 3~
Frequency Hz 50 50 50 50
Voltage V 400 400 400 400
Minimum % -10% -10% -10% -10%
Power Supply
Voltage ToleranceMaximum % +10% +10% +10% +10%
Maximum starting current A 979 979 1032 1032
Nominal running current cooling A 575 627 678 729
Maximum running current A 689 749 814 877Unit
Maximum current for wires sizing A 758 824 895 965
Phase 3~ 3~ 3~ 3~
Voltage V 400 400 400 400
Minimum % -10% -10% -10% -10%Voltage Tolerance
Maximum % +10% +10% +10% +10%
Maximum running current A1)325
2)388
1)388
2)388
1)388
2)458
1)458
2)458
Compressor
Starting method Open Star-Delta Allowed voltage tolerance ± 10%. Voltage unbalance between phases must be within ± 3%.
Nominal current in cooling mode is referred to installation with 25kA short circuit current and is basedon the following conditions: evaporator 12°C/7°C; ambient 35°C.
Maximum starting current: starting current of biggest compressor + 75% of maximum current of theother compressor.
Maximum current for wires sizing: (compressors full load ampere) x 1,1.
Notes
Recommended fuses (IEC 269-2: 1.6 times largest compressor fuse size)
Notes: C.C. (cooling capacity) and P.I. (unit power input) are referred to 0,0176m2 °C/kW evaporator fouling factor and 0,0440m2 °C/kWcondenser fouling factor. Rated conditions are for compressors running at nominal frequency. Shaded values are referred to part loadoperation.
Notes: C.C. (cooling capacity) and P.I. (unit power input) are referred to 0,0176m2 °C/kW evaporator fouling factor and 0,0440m2 °C/kWcondenser fouling factor. Rated conditions are for compressors running at nominal frequency. Shaded values are referred to part load
Notes: C.C. (cooling capacity) and P.I. (unit power input) are referred to 0,0176m2 °C/kW evaporator fouling factor and 0,0440m2 °C/kWcondenser fouling factor. Rated conditions are for compressors running at nominal frequency. Shaded values are referred to part load
Notes: C.C. (cooling capacity) and P.I. (unit power input) are referred to 0,0176m2 °C/kW evaporator fouling factor and 0,0440m2 °C/kWcondenser fouling factor. Rated conditions are for compressors running at nominal frequency. Shaded values are referred to part loadoperation.
Notes: C.C. (cooling capacity) and P.I. (unit power input) are referred to 0,0176m2 °C/kW evaporator fouling factor and 0,0440m2 °C/kWcondenser fouling factor. Rated conditions are for compressors running at nominal frequency. Shaded values are referred to part load
Notes: C.C. (cooling capacity) and P.I. (unit power input) are referred to 0,0176m2 °C/kW evaporator fouling factor and 0,0440m2 °C/kWcondenser fouling factor. Rated conditions are for compressors running at nominal frequency. Shaded values are referred to part load
WarningInstallation and maintenance are to be performed only by qualified personnel who are familiar with local codes
and regulations, and who are experienced with this type of equipment. Must be avoided the unit installation inplaces that could be considered dangerous for all the maintenance operations.
HandlingThe chiller is mounted on heavy wooden skids to protect the unit from accidental damage and to permit easy
handling and moving. It is recommended that all moving and handling be performed with the skids under the
unit when possible and that the skids not be removed until the unit is in the final location.
Spreader bars must be used to protect the control cabinet and the other areas of the chiller.
Location A levelled and sufficiently strong floor is required. If necessary, additional structural members should be
provided to transfer the weight of the unit to the nearest beams.
Rubber-in-shear isolators can be furnished and field placed under each corner of the package. A rubber anti–
skid pad should be used under isolators if hold-down bolts are not used. Vibration isolator in all water piping
connected to the chiller are recommended to avoid straining the piping and transmitting vibration and noise.
To supply and install, where specified in the project n° ………. unit(s) water cooled chiller with cooling capacityof ………. kW, to cool ………. l/sec. of water from ………. °C to ………. °C, condenser entering watertemperature ..........°C, condenser leaving water temperature ..........°C.The unit should work with electricity at ………. V, 3ph, 50Hz. The electrical power absorbed should not exceed………. kW. The units EER will be at least ………. at the working conditions of the project. Part load EER will beat least ………. at the working conditions of the project.The units will have 1 or 2 independent refrigerant circuits, and the respective electronic microprocessor willallow the starting of the compressors. Each chiller will be factory assembled and protected by an epoxy paint.The unit will be tested at full load in the factory at the nominal working conditions and water temperatures.Before shipment a full test will be held to avoid any losses. Chiller will be delivered to the job site completelyassembled and charged with refrigerant and oil.Comply with the manufacturer instructions for rigging and handling equipment.
GENERAL
All units should be designed and manufactured in accordance with applicable selections of the following whichare equivalent to American Air-conditioning industry applicable codes:
Rating of chillers EN 12055
Construction of pressure vessel Pressure Equipment 97/23/EC (PED)
Each chiller consist of single or multiple semi-hermetic rotary screw compressor, direct expansion evaporator,water-cooled condenser section, control system and all components necessary for safe and controlled unitoperation.
NOISE LEVEL AND VIBRATIONS
Sound pressure level at 1 meter distance in free field, semispheric conditions, shall not exceed ………dBA. The
sound pressure levels must be rated in accordance to ISO 9614-2. Other types of rating unacceptable. Vibration
level should not exceed 2 mm/s.
DIMENSIONSUnit length shall not exceed ………. mm, unit width shall not exceed ………. mm, unit height shall not exceed
………. mm.
CHILLER COMPONENTS
Compressors
The compressors shall be field serviceable, semi-hermetic, single-screw type with one main helical rotor
meshing with two opposed gaterotor. Twin-screw compressor will no be accepted because of the large
bearing loads inherent with this design. For a Single-screw compressor the two exactly opposed
gaterotors create two exactly opposed compression cycles which results in balanced forces acting on
the rotor compressor. The gaterotors will be constructed of a carbon impregnated engineered
composite material. The gaterotor supports will be constructed of cast iron.
The oil injection shall be used for these compressors in order to get high EER also at high condensing
pressure and low sound pressure levels in each load condition.
Refrigerant system differential pressure shall provide oil flow through service replaceble, 0.5 micron, full
flow, cartridge type oil filter internal to compressor. Filter bypass or oil pump not acceptable.
The compressor’s oil cooling must be realized by liquid injection. External dedicated heat exchanger
and additional piping to carry the oil from the compressor to heat exchanger and viceversa will be not
accepted.
The compressor shall be direct electrical drive, without gear transmission between the screw and the
electrical motor. The motor’s compressor shall be designed for star/delta. Soft start should be available
as option.
Shall be present two thermal protection realized by a thermistor for high temperature protection to motor
and a thermistor for discharge gas high temperature protection.
The compressor shall be provided with an automatic spring return of capacity control valve to the
minimum load position to ensure compressor starting always at minimum motor load so with the
minimum mechanical stress.
The compressor discharge connection shall be fitted with a check valve and with a stop valve.
The compressor discharge shall be fitted with a head pressure control valve.
Evaporator
The units shall be supplied with shell and tubes counter-flow evaporator single refrigerant pass. It will be
direct expansion with refrigerant inside the tubes and water outside (shell side) with carbon steel tube
sheets, with straight copper tubes that are spirally wound internally for higher efficiencies, expanded on
the tube plates.
The external shell, shall be linked with an electrical heater (option on request) to prevent freezing up to -
28 C ambient temperature, commanded by a thermostat and shall be insulated with flexible, closed cell
polyurethane insulation material.
The evaporator will have 1 or 2 circuits, one for each compressor and shall be single refrigerant pass to
ensure a simplier oil circulation so to ensure always a perfect oil return to the compressor.
Evaporator is manufactured in accordance to PED approval.
Condensers Condensers will be shell and cleanable, through-tube type.
The unit will have one condensers per circuit.
Each condenser shall have a carbon steel and seamless, integrally finned high efficiency copper tubes,
roll expanded into heavy carbon steel tube sheets.
Water heads shall be removable and include vent and drain plugs.
Condensers will come complete with liquid shut-off valve, spring loaded relief valve.
Refrigerant circuit
The unit must have refrigerant circuits completely independent of each other with one compressor percircuit.
Each circuit shall include an: electronic expansion valve, external high efficiency oil separator, a liquidline shut-off valve with charging connection, replaceable core filter-drier, sight glass with moistureindicator and insulated suction line. Suction line and discharge line shut-off valves are available asoption.
Regulation of cooling capacity
Each unit will have a microprocessor for the control of compressor slide valve’s position (2 slide valves,one for each compressor’s cycles).
The slides shall have a stepless motion that allows a unit’s operation with infinitely variable capacitycontrol down to 25% (1 compressor) or down to 12,5% (2 compressors) of the cooling capacity. Thechiller shall be capable of stable operation to a minimum of 25% (1 compressor) or to a minimum of12,5% (2 compressors) of full load without hot gas bypass.
Step unloading unacceptable because of evaporator leaving water temperature fluctuation and lowcompressor’s efficiency at partial load.
The system shall stage the unit based on the leaving water temperature.
Electronic expansion valve allows a simple and perfect control system that quickly interacts at loadvariations. This valve combines two functions: liquid solenoid and electronic expansion valve.
It is managed directly by a microprocessor to mach exactly the plant thermal load.
Thermostatic valve unacceptable because of:
o its limited load range; o higher refrigerant pressure drop;
o because of leaving evaporator water temperature control less good than an electronic device;
o thermal expansion device needs a higher differential pressure between high pressure side andlow pressure side to work correctly. This doesn’t allow to work with low condensing pressureand therefore doesn’t allow to reach the money saving that is possible to have with these chillerworking conditions.
Control panel
Field power connections, control interlock terminals, and unit control system should be centrally located
in an electric panel (IP 54). The Power components and control equipment shall be separately mounted in different compartments
of the control panel.
The Compressor starting method will be star/delta, with an option for Softstart.
Power and starting controls should include fuses and contactors for the compressor.
Operating and safety controls should include energy saving; emergency stop switch; thermal overloadprotection for each compressor motor; high and low pressure cut-out switch (for each refrigerant circuit);anti-freeze thermostat; cut-out switch for each compressor.
All of the information regarding the unit shall be shown on a display with a built-in calendar and clockthat will provide unit scheduling throughout the year.
The following features and functions shall be included:
- resetting chilled water temperature by controlling the return water temperature or by a remote 4-20mA DC signal:
- soft load function to prevent the system from operating at full load during the chilled fluid pulldownperiod;
- password protection of critical parameters of control;- start-to-start and stop-to-start timers to provide minimum compressor off-time with maximum motor
protection;- communication capability with a PC or remote monitoring;- lead-lag selection by manual or automatically by circuit run hours;- double set point for brine unit version;- scheduling via internal time clock to allow programming of a yearly start-stop schedule accommodating
weekends and holidays.
Display Capabilities
The controller as a minimum shall be capable of monitoring and displaying the following data: -
Operating Conditions Alarms
Ent./ Lvg. Evaporator fluid Temp. Phase Monitor
Entering Condenser fluid Temp. Freeze Protection
Operating Chilled Fluid Setpoint Evaporator Flow
Oil / Discharge gas Press. (per comp.) Low Gas Pressure (per comp.)Condensing Press. (per comp.) Transition Fault, (per comp.)